1. Field of the Invention
The present invention relates to a portable mobile unit for alerting a user (or subscriber) of incoming of a signal by means of ringing, and in particular to a portable mobile unit being suitable for alerting of the condition when a phone call is coming in, through such the ringing sound.
2. Prior Art
With conventional cellular phones, it is common to generate the ringing sound for alerting of incoming phone calls, from various tone data which are obtained by coding the tone signals digitally. The users of the cellular phone can easily recognize the incoming call (i.e., arrival of the telephone call) to her/his own cellular phone by the ringing sound. Recently, users of such cellular phones are increasing in number very rapidly, which brings about cases that people having their own cellular phones happen to be within the same place or area very often this results in confusion of the incoming call with that to others, and then there occurs a demand or a necessity for discriminating or differentiating the ringing sound of each the cellular phone from others. For example, a melody generator, which is capable of producing different melodies according to a choice of the user, is widely prevailed and getting popular among cellular phone users to discriminate her/his cellular phone from others'. with which each user can produce her/his own melody, thereby obtaining the discrimination thereof from others. Further, as shown in Japanese Patent Laid-open No. Hei 10-4442 (1998), there is already known an apparatus having a function of renewing the melody by means of download thereof, and also, as shown in Japanese Patent Laid-open No. Hei 08-251258 (1996), there is already known an apparatus having a means for producing its own original sound for alerting of the incoming call, by taking in sounds from an external microphone in advance. Conventionally, for discriminating the ringing sound, a beep sound with its frequency range simply expanded or with its tempo made variable is used so as to enable the melody to sound more natural than that of a previous type using a beep sound which sounds rather mechanical. In addition, an apparatus utilizing a FM sound source, which can play tones of musical instruments by synthesizing the sounds from a sound database is manufactured or put on a market recently. However, this apparatus is designed to synthesize not vocal sounds but particular musical instrumental sounds. Also, a PCM sound source enables to produce the vocal sounds or sound effects (such as, mimic sounds), which can increase the number of the alerting sounds infinitely. However, it brings about a demerit of requiring data capacity too much, particularly, for the cellular phone, which is demanded to be light-weighted and small-sized.
Also, alerting used in another purpose, such as distinguishing callers by changing the ringing sound or by changing a light-emission pattern instead, is shown in Japanese Patent Laid-open No. Hei 09-312684 (1997). This improves utility value thereof, because the user can know who is calling (i.e., a caller) only by hearing the ringing sound.